1. Field of the Invention
The invention relates to a biological control agent for control of fungal diseases in plants.
2. Description of the Prior Art
Gliocladium virens has been recognized as a mycoparasite and antibiotic-producing antagonist of plant pathogens, and has been used as an effective biocontrol agent of several soilborne root or seedling diseases [Aluko and Hering, 1970, Trans. Br. Mycol. Soc., 55:173-179; Beagle-Ristaino and Papavizas, 1985, Phytopathology, 75:560-564; Howell, 1982, Phytopathology, 72:496-498; Howell and Stipanovic, 1983, Can. J. Microbiol., 29:321-324; Weindling and Fawcett, 1936, Hilgardia, 10:1-16; and Wright, 1956, Plant Soil, 8:132-140]. G. virens produces gliotoxin and gliovirin, which are particularly effective antifungal antibiotics, as well as the antibacterial compound heptelidic acid and the antifungal compound viridin.
In addition to its use as an antifungal biocontrol agent, G. virens has also been employed as a mycoherbicide [Jones et al., 1988, Weed Science, 36:683-687; and Howell and Stipanovic, 1984, Phytopathology, 74:1346-1349]. Herbicidal activity has been attributed to the production of viridiol, a steroidal phytotoxin.
Unfortunately, viridiol has not only been shown to be phytotoxic to weeds such as pigweed, but also to valuable crop plants such as cotton seedlings [Howell et al., Phytopathology, 74:1346-1349 (1984)]. Thus, the production of the phytotoxic compound viridiol may severely restrict the use of G. virens as a biocontrol agent for the control of plant diseases, limiting the amount of G. virens that can be applied to crops.